Polyester Resin Terminal Structure for Photoreceptor Adhesion
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Solution Overview
Problem
The existing use of polyester resin as a binder in electrophotographic photoreceptors often results in the photosensitive layer being easily peeled off due to degraded adhesiveness and insufficient abrasion resistance, particularly when the resin contains chain hydrocarbon groups with 5 or more carbon atoms at the terminal.
Innovation Solution
An electrophotographic photoreceptor with a lamination or single layer type photosensitive layer containing a polyester resin with a specific terminal structure, where the weight-average molecular weight and thickness of the charge transport layer or single layer type photosensitive layer are optimized, along with a charge generation and charge transport material, to achieve enhanced adhesion and abrasion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a polyester resin is used as a binder resin of a photosensitive layer, then abrasion resistance of the photosensitive layer is enhanced, but the photosensitive layer may be easily peeled off from the electrophotographic photoreceptor
Solution Approach 1:
The patent changes the chemical structure parameters of the polyester resin by specifying terminal group compositions (combinations of carboxyl, hydroxyl, and ester groups in specific ratios) and molecular weight ranges (70,000-400,000), thereby achieving both enhanced abrasion resistance and maintained adhesiveness simultaneously
Solution Approach 2:
The patent creates a composite binder resin system by combining polyester resin with specific charge transport materials (such as triphenylamine derivatives and carbazole derivatives) in defined weight ratios, where the composite structure provides both mechanical durability and interfacial bonding properties
2Strength
If the photosensitive layer is made with enhanced abrasion resistance, then durability is improved, but further enhancement of abrasion resistance is required
Solution Approach 1:
The patent optimizes the weight-average molecular weight of the polyester resin within the range of 70,000-400,000 and controls the terminal group composition (carboxyl: 10-50%, hydroxyl: 10-50%, ester: 20-80%), thereby achieving a balance between abrasion resistance and peel resistance that cannot be obtained with conventional polyester resins
Solution Approach 2:
The patent applies different functional groups at the terminal positions of the polyester resin chains (carboxyl, hydroxyl, and ester groups in specific proportions) to provide localized chemical properties that enhance both surface durability and interfacial adhesion simultaneously
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The optimized configuration significantly reduces peeling and enhances abrasion resistance of the photosensitive layer, maintaining excellent electrical properties by improving the compatibility and dispersibility of the charge transport material within the polyester resin.
Implementation Method 1
a binder resin in the photosensitive layer is a polyester resin having a specific terminal structure
Implementation Method 2
the charge transport layer contains a polyester resin and a charge transport material
Implementation Method 3
a single layer type photosensitive layer contains a polyester resin, a charge generation material, and a charge transport material
Data Source
AI summary
An electrophotographic photoreceptor includes a conductive substrate, and a lamination type photosensitive layer disposed on the conductive substrate and including a charge generation layer and a charge transport layer, in which the charge transport layer contains a polyester resin having a structure represented by Formula (1) at a terminal and a charge transport material, and in a case where a weight-average molecular weight Mw of the polyester resin is defined as A (×10,000), a value of a ratio M1/M2 of a mass M1 of the charge transport material to a mass M2 of an entire charge transport layer is defined as Cs, and an average thickness of the charge transport layer is defined as Ds (μm), expressions of 7≤A≤40, 0.28≤Cs≤0.55, 27≤Ds≤50, and 5.0≤(A×Ds)/(Cs×100)≤70 are satisfied,in Formula (1), nd represents an integer of 0 or greater and 4 or less, nd number of Rd's each independently represent a hydrocarbon group having 1 or more and 4 or less carbon atoms, L represents an ether bond or a —O—C(═O)— group, and * represent a bonding portion.